/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/Public/Online/LobbiesCommon.h
Change the schema applied to the lobby and member attributes. Only the lobby leader may change the schema. Existing attributes not present in the new schema will be cleared.
virtual [TOnlineAsyncOpHandle](API\Plugins\OnlineServicesInterface\Online\TOnlineAsyncOpHandle)< [FModifyLobbySchema](API\Plugins\OnlineServicesInterface\Online\FModifyLobbySchema) > ModifyLobbySchema ( [FModifyLobbySchema::Params](API\Plugins\OnlineServicesInterface\Online\FModifyLobbySchema\Params) && Params )